The present invention concerns seating units having a reclineable back, and more particularly concerns seating units having a reclineable back and a forwardly movable/tiltable seat that moves with a synchronous movement as the back is reclined.
Modern customers and chair purchasers demand a wide variety of chair options and features, and a number of options and features are often designed into chair seats. However, improvement in seats is desired so that a seated user""s weight is adequately supported on the chair seat, but simultaneously so that the thigh area of a seated user is comfortably, adjustably supported in a manner that adequately allows for major differences in the shape and size of a seated user""s buttocks and thighs. Additionally, it is important that such options and features be incorporated into the chair construction in a way that minimizes the number of parts and maximizes the use of common parts among different options, maximizes efficiencies of manufacturing and assembling, maximizes ease of adjustment and the logicalness of adjustment control positioning, and yet that results in a visually pleasing design.
More specifically, in regard to synchrotilt chairs where the seat and the back pivot with synchronized angular movements, many synchrotilt chairs have been designed to pivot seats rearwardly as a user reclines. However, often these known seat constructions pivot about a seat pivot axis located rearward of a front edge of the seat. The result is that the knees of a seated user are lifted, resulting in undesired pressure on the seated user""s thighs upon recline. Designing a flexible front lip into the seat does not fully resolve the undesired thigh pressure since the thighs are not supported only at a front lip of the seat, but instead are supported along at least about half of the seat. Locating a flexible zone substantially rearwardly in a seat, such as rearward of the hip joint of a seated user, also does not resolve the situation since the weight of a seated user""s upper torso tends to cause a seated user to slip/slide downwardly and forwardly off of a chair back when the chair back is reclined. This in turn causes the seated user to slide forward and off of the seat unless the seat includes a rear zone shaped and oriented to support the seated user against such forward slip/slide movement. The problem is compounded by the fact that the hip joint of different seated user""s are not always located in the same relative location on the chair seat, such that one seat design may work well for one seated user, but not for another seated user.
Even if the thigh support problems of a seat construction are solved, it is desired to improve the location of the seat construction relative to its surroundings. For example, a synchrotilt chair is described in U.S. Pat. Nos. 5,050,931; 4,744,603; 4,776,633; and 5,567,012 (to Knoblock et al.) having a base assembly with a control, a reclineable back pivoted to the control, and a seat operably mounted to the back and control for synchronous motion as the back is reclined. This prior art chair incorporates a semi-rigid flexible shell that, in combination with the chair support structure, provides a highly-controlled postural support during the body movements associated with tasks/work (e.g., when the back is in an upright position) and during the body movements associated with recline/relaxation (e.g., when the chair is in a reclined position). This prior art chair moves a seated user""s upper body away from the user""s work surface as the user reclines, thus providing the user with more area to stretch. However, we have discovered that often users want to remain close to their work surface and want to continue to work at the work surface, even while reclining and relaxing their body and while having continued postural support. In order to do this in the synchrotilt chair of U.S. Pat. No. 5,050,931, users must scoot their chair forwardly after they recline so that they can still easily reach their work surface. They must also push away when they move back to an upright position to avoid being pushed against their work surface. xe2x80x9cScootingxe2x80x9d back and forth once or twice is perhaps not a serious problem, but often users, such as office workers using computers, are constantly moving between upright and reclined positions, such that the process of repeatedly scooting back and forth becomes annoying and disconcerting. In fact, moving around and not staying in a single static position is important to good back health in workers whose jobs require a lot of sitting.
Another disadvantage of moving a seated user""s upper body significantly rearwardly upon recline is that the user""s overall center of gravity moves rearward. By providing a more constant center of gravity, it is possible to design a reclineable chair having greater recline or height adjustment without sacrificing the overall stability of the chair. Also, reclineable chairs that move a seated user""s upper body significantly rearwardly have a relatively large footprint, such that these chairs may bump into furniture or a wall when used in small offices or in a compact work area. Still another disadvantage is that large springs are required in these existing reclineable chairs for back support, which springs are difficult to adjust due to the forces generated by the springs. However, the tension of these springs preferably should be adjustable so that heavier and lighter weight users can adjust the chair to provide a proper amount of support.
Concurrently, seated users want to be able to easily adjust the spring tension for providing support to the back during recline. Not only do heavier/larger people need greater/firmer back support than lighter/smaller people, but the amount of support required changes at a greater rate during recline. Specifically, lighter/smaller people need a lesser initial level of support as they begin to recline and need a moderately increased level of support as they continue to recline; while heavier/larger people need a significantly higher minimum initial level of support as they begin to recline and need a significantly increased level of support as they continue to recline. Restated, it is desirable to provide a chair that is easily adjustable in its initial level of support to the back during initial recline and that automatically also adjusts the rate of increase in support during recline. Further, it is desirable to provide a mechanism to allow such an easy adjustment (1) while seated; (2) by a relatively weaker person; (3) using easily manipulatable adjustment controls; and (4) while doing so with a control that is not easily damaged by a relatively strong person who may xe2x80x9covertorquexe2x80x9d the control. Further, a compact spring arrangement is desired to provide optimal appearance and to minimize material cost and part size.
Accordingly, a chair construction solving the aforementioned problems is desired.
In one aspect of the present invention, a seating unit including a base assembly having a control housing with opposing flanges defining upper edges and lubricous caps attached to the upper edges of the control housing, the lubricous caps including upper surfaces defining tracks for slidably engaging a slide member. A back frame is pivoted to the base assembly at a back pivot for movement between upright and reclined positions. A seat support structure is operably supported on the base assembly and the back frame includes a slide member slidably engaging the control housing for generally horizontal sliding movement. The seat support structure further includes a seat carrier pivoted to the slide member at a front seat pivot and also pivoted to the back frame at a rear seat pivot.
In one aspect of the present invention, a seating unit including a base assembly having a control housing, a back frame pivoted to the base assembly at a back pivot for movement between upright and reclined positions, and a seat support structure operably supported on the base assembly. The back frame includes a slide member slidably engaging the control housing for generally horizontal sliding movement and includes a seat carrier pivoted to the slide member at a front seat pivot and also pivoted to the back frame at a rear seat pivot. A spring mechanism is positioned in the control housing, the spring mechanism being operably connected to the slide member. The spring mechanism includes a spring positioned transversely in the control housing, and further includes a lever operably pivoted to the control housing, the lever having one end operably engaging the spring and another end operably engaging the seat support structure. A pivot member is provided, and the pivot member and the lever have interfacing surfaces, at least one of which is curvilinear, so that the arrangement operates like a rack-and-pinion. The pivot member is adjustable to vary a fulcrum point on the lever to adjust a length of a moment arm over which the spring acts.
In another aspect of the present invention, a seating unit includes a base assembly having a control housing, a back frame pivoted to the base assembly at a back pivot for movement between upright and reclined positions, and a seat support structure operably supported on the base assembly. The back frame includes a slide member slidably engaging the control housing for generally horizontal sliding movement and includes a seat carrier pivoted to the slide member at a front seat pivot and also pivoted to the back frame at a rear seat pivot. A seat shell is slidably supported on the seat support structure for selective depth adjustment, whereby a depth of the seat shell can be selectively adjusted relative to the back frame.
In another aspect of the present invention, a seating unit includes a base assembly having a control housing with sidewalls defining a track, a seat having a front portion with bearings slidably engaging the track and having a rear portion, and a back. The seat includes a seat shell having a flexibly supported front portion. The back is pivoted to the base assembly and separately pivoted to the seat for movement between an upright position and a reclined position. The rear portion of the seat is pivoted to the back so that the seat moves forwardly and the seat rear portion moves forwardly and downwardly with a synchronous motion as the back is reclined. A spring mechanism is positioned in the central housing and operably connected to the seat for biasing the seat rearwardly. The spring mechanism includes an extendable/compressible spring positioned in the control housing and a lever pivoted to the control housing. The lever defines a moment arm with the spring for transmitting energy from the spring to the seat to bias the back to the upright position. A gas spring is operably connected between the front portion of the shell and a remaining portion of the seat adapted to carry the weight of a typical seated adult user. The gas spring is operable to adjust a position of the front portion relative to the remaining portion of the seat.
In another aspect of the present invention, a seating unit including a base assembly having a control housing with sidewalls defining a track, and a seat having a front portion with bearings slidably engaging the track and having a rear portion. The seat includes a seat shell having a flexibly supported front portion. A back is pivoted to the base assembly and separately pivoted to the seat for movement between an upright position and a reclined position. The rear portion of the seat is pivoted to the back so that the seat moves forwardly and the seat rear portion moves forwardly and downwardly with a synchronous motion as the back is reclined. A spring mechanism is positioned in the central housing and operably connected to the seat for biasing the seat rearwardly. The spring mechanism includes an extendable/compressible spring positioned in the control housing and a lever pivoted to the control housing. The lever defines a moment arm with the spring for transmitting energy from the spring to the seat to bias the back to the upright position. A leaf spring is positioned between and resiliently-supporting the front section and a remaining portion of the seat.
In another aspect of the present invention, a seating unit includes a base assembly having a control housing with sidewalls defining a track, and a seat having a front portion with bearings slidably engaging the track and having a rear portion. The seat includes a seat shell and a depth-adjustment structure for adjusting a depth of the seat shell relative to the back. A back pivoted to the base assembly and separately pivoted to the seat for movement between an upright position and a reclined position. The rear portion of the seat is pivoted to the back so that the seat moves forwardly and the seat rear portion moves forwardly and downwardly with a synchronous motion as the back is reclined. A spring mechanism is positioned in the central housing and operably connected to the seat for biasing the seat rearwardly. The spring mechanism includes an extendable/compressible spring positioned in the control housing and a lever pivoted to the control housing and defining a moment arm with the spring for transmitting energy from the spring to the seat to bias the back to the upright position.
In another aspect of the present invention, a seating unit includes a base assembly having a control housing, a reclineable back frame pivoted to the base assembly for movement between upright and fully reclined positions, and a seat slidably supported on the control housing and pivotally supported on the back frame. A variable back-stop mechanism is operably supported on the base assembly for engaging the seat to stop the seat and concurrently stop recline of the back at selected positions prior to reaching the fully reclined position. The variable back-stop mechanism includes a seat-engaging member and an actuator lever for adjustably moving the seat-engaging member, the seat-engaging member and the lever including intermeshing teeth for providing slip-free engagement.
In another aspect of the present invention, a seating unit includes a base assembly having a control housing, a reclineable back frame pivoted to the base assembly for movement between upright and fully reclined positions, and a seat slidably supported on the control housing and pivotally supported on the back frame. A variable back-stop mechanism is operably supported on the base assembly for engaging the seat to stop the seat and concurrently stop recline of the back at selected positions prior to reaching the fully reclined position. The variable back-stop mechanism includes a movable cam with steps shaped to selectively engage the seat, and further includes a spring detent for holding the cam in a selected stopping position where a particular one of the steps is positioned to engage the seat. An actuator connected to the cam for rotating the cam to select the particular one step, the actuator including a lever pivoted to the control housing, the lever, and the cam including intermeshing teeth.
In still another aspect of the present invention, a seating unit includes a base assembly having a control housing, a reclineable back frame pivoted to the base assembly for movement between upright and fully reclined positions, and a seat slidably supported on the control housing and pivotally supported on the back frame. A variable back-stop mechanism is operably supported on the base assembly for engaging the seat to stop the seat and concurrently stop recline of the back at selected positions prior to reaching the fully reclined position. The variable back-stop mechanism includes a movable cam with steps shaped to selectively engage the seat. The cam further includes an undulated surface adapted to engage a detent for selectively holding the steps in position to engage the seat, and still further includes teeth adapted to engage mating teeth on an actuator for operating the cam.
In still another aspect, a seat construction for a seating unit includes a resiliently-flexible seat shell having a front section configured to comfortably support thighs of a typical seated adult user, a rear section configured to comfortably support buttocks of a seated adult user and to comfortably support a majority of the weight of the seated adult user, and a flexible intermediate section connecting the front and rear sections. The front section is located about midway or forward therefrom on the seat shell and generally forward of the expected location of a seated adult user""s hip joint so that the seated adult user""s weight is substantially carried by the rear section for most adult users. A seat cushion is supported on the seat shell, and a pan-shaped seat carrier supports the rear section of the shell. The seat carrier includes a forwardly-extending section extending under the flexible intermediate section and that is characteristically spaced below and not connected to the flexible intermediate section. An adjustable thigh-flex support mechanism operably supports the front section of the seat shell on the forwardly-extending section of the seat carrier, so that the front section is adjustable relative to the rear section to provide optimal thigh pressure and support to the seated adult user, the adjustable thigh-flex support mechanism including a pre-tensioned, transverse leaf spring.
In still another aspect of the present invention, a seat construction for a seating unit includes a resiliently-flexible seat shell having a front section configured to comfortably support thighs of a typical seated adult user, a rear section configured to comfortably support buttocks of a seated adult user and to comfortably support a majority of the weight of the seated adult user, and a flexible intermediate section connecting the front and rear sections. The front section is located about midway or forward therefrom on the seat shell and generally forward of the expected location of a seated adult user""s hip joint so that the seated adult user""s weight is substantially carried by the rear section for most adult users. A seat cushion is supported on the seat shell. A pan-shaped seat carrier supports the rear section of the shell. The seat carrier includes a forwardly-extending section extending under the flexible intermediate section and that is characteristically spaced below and not connected to the flexible intermediate section. An adjustable thigh-flex support mechanism operably supports the front section of the seat shell on the forwardly-extending section of the seat carrier, so that the front section is adjustable relative to the rear section to provide optimal thigh pressure and support to the seated adult user. The adjustable thigh-flex support mechanism includes a bent rod axle and a releasable, lockable gas spring for rotating the bent rod axle and thereafter holding the bent rod axle in a selected orientation.
In a seating unit having a reclineable back and a movable seat operably supported for synchronous movement with the back, an inventive improvement includes a seat carrier having a T-shaped body including front and rear sections and including a linear bearing positioned on each side of the front section and each side of the rear section. The seat carrier includes pivots adapted to pivotally mount the seat carrier to a support for movably supporting the movable seat relative to the reclineable back. A pan-shaped seat frame is constructed to support a seat cushion and a seated user. The seat frame includes a bottom panel with flat surfaces slidably engaging associated ones of the linear bearings, whereby the seat frame is depth-adjustable on the seat carrier
In another aspect of the present invention, a seating unit including a base assembly having a control housing having at least one up flange and a lubricous bearing supported atop each up flange, a back frame pivoted to the base assembly at a back pivot for movement between upright and reclined positions, and a seat support structure operably supported on the base assembly. The back frame includes a slide member slidably engaging the lubricous bearing of each up flange for generally horizontal sliding movement and includes a seat carrier pivoted to the slide member at a front seat pivot and also pivoted to the back frame at a rear seat pivot.
These and other features and advantages of the present invention will be further understood and appreciated by those skilled in the art by reference to the following specification, claims, and appended drawings.